| /* |
| * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> |
| * Copyright (c) 2016 Alexandra Hájková |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file |
| * bitstream reader API header. |
| */ |
| |
| #ifndef AVCODEC_GET_BITS_H |
| #define AVCODEC_GET_BITS_H |
| |
| #include <stdint.h> |
| |
| #include "libavutil/common.h" |
| #include "libavutil/intreadwrite.h" |
| #include "libavutil/avassert.h" |
| |
| #include "defs.h" |
| #include "mathops.h" |
| #include "vlc.h" |
| |
| /* |
| * Safe bitstream reading: |
| * optionally, the get_bits API can check to ensure that we |
| * don't read past input buffer boundaries. This is protected |
| * with CONFIG_SAFE_BITSTREAM_READER at the global level, and |
| * then below that with UNCHECKED_BITSTREAM_READER at the per- |
| * decoder level. This means that decoders that check internally |
| * can "#define UNCHECKED_BITSTREAM_READER 1" to disable |
| * overread checks. |
| * Boundary checking causes a minor performance penalty so for |
| * applications that won't want/need this, it can be disabled |
| * globally using "#define CONFIG_SAFE_BITSTREAM_READER 0". |
| */ |
| #ifndef UNCHECKED_BITSTREAM_READER |
| #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER |
| #endif |
| |
| #ifndef CACHED_BITSTREAM_READER |
| #define CACHED_BITSTREAM_READER 0 |
| #endif |
| |
| typedef struct GetBitContext { |
| const uint8_t *buffer, *buffer_end; |
| #if CACHED_BITSTREAM_READER |
| uint64_t cache; |
| unsigned bits_left; |
| #endif |
| int index; |
| int size_in_bits; |
| int size_in_bits_plus8; |
| } GetBitContext; |
| |
| static inline unsigned int get_bits(GetBitContext *s, int n); |
| static inline void skip_bits(GetBitContext *s, int n); |
| static inline unsigned int show_bits(GetBitContext *s, int n); |
| |
| /* Bitstream reader API docs: |
| * name |
| * arbitrary name which is used as prefix for the internal variables |
| * |
| * gb |
| * getbitcontext |
| * |
| * OPEN_READER(name, gb) |
| * load gb into local variables |
| * |
| * CLOSE_READER(name, gb) |
| * store local vars in gb |
| * |
| * UPDATE_CACHE(name, gb) |
| * Refill the internal cache from the bitstream. |
| * After this call at least MIN_CACHE_BITS will be available. |
| * |
| * GET_CACHE(name, gb) |
| * Will output the contents of the internal cache, |
| * next bit is MSB of 32 or 64 bits (FIXME 64 bits). |
| * |
| * SHOW_UBITS(name, gb, num) |
| * Will return the next num bits. |
| * |
| * SHOW_SBITS(name, gb, num) |
| * Will return the next num bits and do sign extension. |
| * |
| * SKIP_BITS(name, gb, num) |
| * Will skip over the next num bits. |
| * Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER. |
| * |
| * SKIP_CACHE(name, gb, num) |
| * Will remove the next num bits from the cache (note SKIP_COUNTER |
| * MUST be called before UPDATE_CACHE / CLOSE_READER). |
| * |
| * SKIP_COUNTER(name, gb, num) |
| * Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS). |
| * |
| * LAST_SKIP_BITS(name, gb, num) |
| * Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER. |
| * |
| * BITS_LEFT(name, gb) |
| * Return the number of bits left |
| * |
| * For examples see get_bits, show_bits, skip_bits, get_vlc. |
| */ |
| |
| #if CACHED_BITSTREAM_READER |
| # define MIN_CACHE_BITS 64 |
| #elif defined LONG_BITSTREAM_READER |
| # define MIN_CACHE_BITS 32 |
| #else |
| # define MIN_CACHE_BITS 25 |
| #endif |
| |
| #if !CACHED_BITSTREAM_READER |
| |
| #define OPEN_READER_NOSIZE(name, gb) \ |
| unsigned int name ## _index = (gb)->index; \ |
| unsigned int av_unused name ## _cache |
| |
| #if UNCHECKED_BITSTREAM_READER |
| #define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb) |
| |
| #define BITS_AVAILABLE(name, gb) 1 |
| #else |
| #define OPEN_READER(name, gb) \ |
| OPEN_READER_NOSIZE(name, gb); \ |
| unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8 |
| |
| #define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8 |
| #endif |
| |
| #define CLOSE_READER(name, gb) (gb)->index = name ## _index |
| |
| # ifdef LONG_BITSTREAM_READER |
| |
| # define UPDATE_CACHE_LE(name, gb) name ## _cache = \ |
| AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7) |
| |
| # define UPDATE_CACHE_BE(name, gb) name ## _cache = \ |
| AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7)) |
| |
| #else |
| |
| # define UPDATE_CACHE_LE(name, gb) name ## _cache = \ |
| AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7) |
| |
| # define UPDATE_CACHE_BE(name, gb) name ## _cache = \ |
| AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) |
| |
| #endif |
| |
| |
| #ifdef BITSTREAM_READER_LE |
| |
| # define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb) |
| |
| # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) |
| |
| #else |
| |
| # define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb) |
| |
| # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) |
| |
| #endif |
| |
| #if UNCHECKED_BITSTREAM_READER |
| # define SKIP_COUNTER(name, gb, num) name ## _index += (num) |
| #else |
| # define SKIP_COUNTER(name, gb, num) \ |
| name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) |
| #endif |
| |
| #define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index)) |
| |
| #define SKIP_BITS(name, gb, num) \ |
| do { \ |
| SKIP_CACHE(name, gb, num); \ |
| SKIP_COUNTER(name, gb, num); \ |
| } while (0) |
| |
| #define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) |
| |
| #define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num) |
| #define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num) |
| |
| #define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num) |
| #define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num) |
| |
| #ifdef BITSTREAM_READER_LE |
| # define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num) |
| # define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num) |
| #else |
| # define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num) |
| # define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num) |
| #endif |
| |
| #define GET_CACHE(name, gb) ((uint32_t) name ## _cache) |
| |
| #endif |
| |
| static inline int get_bits_count(const GetBitContext *s) |
| { |
| #if CACHED_BITSTREAM_READER |
| return s->index - s->bits_left; |
| #else |
| return s->index; |
| #endif |
| } |
| |
| #if CACHED_BITSTREAM_READER |
| static inline void refill_32(GetBitContext *s, int is_le) |
| { |
| #if !UNCHECKED_BITSTREAM_READER |
| if (s->index >> 3 >= s->buffer_end - s->buffer) |
| return; |
| #endif |
| |
| if (is_le) |
| s->cache = (uint64_t)AV_RL32(s->buffer + (s->index >> 3)) << s->bits_left | s->cache; |
| else |
| s->cache = s->cache | (uint64_t)AV_RB32(s->buffer + (s->index >> 3)) << (32 - s->bits_left); |
| s->index += 32; |
| s->bits_left += 32; |
| } |
| |
| static inline void refill_64(GetBitContext *s, int is_le) |
| { |
| #if !UNCHECKED_BITSTREAM_READER |
| if (s->index >> 3 >= s->buffer_end - s->buffer) |
| return; |
| #endif |
| |
| if (is_le) |
| s->cache = AV_RL64(s->buffer + (s->index >> 3)); |
| else |
| s->cache = AV_RB64(s->buffer + (s->index >> 3)); |
| s->index += 64; |
| s->bits_left = 64; |
| } |
| |
| static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le) |
| { |
| uint64_t ret; |
| av_assert2(n>0 && n<=63); |
| if (is_le) { |
| ret = s->cache & ((UINT64_C(1) << n) - 1); |
| s->cache >>= n; |
| } else { |
| ret = s->cache >> (64 - n); |
| s->cache <<= n; |
| } |
| s->bits_left -= n; |
| return ret; |
| } |
| |
| static inline unsigned show_val(const GetBitContext *s, unsigned n) |
| { |
| #ifdef BITSTREAM_READER_LE |
| return s->cache & ((UINT64_C(1) << n) - 1); |
| #else |
| return s->cache >> (64 - n); |
| #endif |
| } |
| #endif |
| |
| /** |
| * Skips the specified number of bits. |
| * @param n the number of bits to skip, |
| * For the UNCHECKED_BITSTREAM_READER this must not cause the distance |
| * from the start to overflow int32_t. Staying within the bitstream + padding |
| * is sufficient, too. |
| */ |
| static inline void skip_bits_long(GetBitContext *s, int n) |
| { |
| #if CACHED_BITSTREAM_READER |
| skip_bits(s, n); |
| #else |
| #if UNCHECKED_BITSTREAM_READER |
| s->index += n; |
| #else |
| s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); |
| #endif |
| #endif |
| } |
| |
| #if CACHED_BITSTREAM_READER |
| static inline void skip_remaining(GetBitContext *s, unsigned n) |
| { |
| #ifdef BITSTREAM_READER_LE |
| s->cache >>= n; |
| #else |
| s->cache <<= n; |
| #endif |
| s->bits_left -= n; |
| } |
| #endif |
| |
| /** |
| * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB). |
| * if MSB not set it is negative |
| * @param n length in bits |
| */ |
| static inline int get_xbits(GetBitContext *s, int n) |
| { |
| #if CACHED_BITSTREAM_READER |
| int32_t cache = show_bits(s, 32); |
| int sign = ~cache >> 31; |
| skip_remaining(s, n); |
| |
| return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign; |
| #else |
| register int sign; |
| register int32_t cache; |
| OPEN_READER(re, s); |
| av_assert2(n>0 && n<=25); |
| UPDATE_CACHE(re, s); |
| cache = GET_CACHE(re, s); |
| sign = ~cache >> 31; |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; |
| #endif |
| } |
| |
| #if !CACHED_BITSTREAM_READER |
| static inline int get_xbits_le(GetBitContext *s, int n) |
| { |
| register int sign; |
| register int32_t cache; |
| OPEN_READER(re, s); |
| av_assert2(n>0 && n<=25); |
| UPDATE_CACHE_LE(re, s); |
| cache = GET_CACHE(re, s); |
| sign = sign_extend(~cache, n) >> 31; |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| return (zero_extend(sign ^ cache, n) ^ sign) - sign; |
| } |
| #endif |
| |
| static inline int get_sbits(GetBitContext *s, int n) |
| { |
| register int tmp; |
| #if CACHED_BITSTREAM_READER |
| av_assert2(n>0 && n<=25); |
| tmp = sign_extend(get_bits(s, n), n); |
| #else |
| OPEN_READER(re, s); |
| av_assert2(n>0 && n<=25); |
| UPDATE_CACHE(re, s); |
| tmp = SHOW_SBITS(re, s, n); |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| #endif |
| return tmp; |
| } |
| |
| /** |
| * Read 1-25 bits. |
| */ |
| static inline unsigned int get_bits(GetBitContext *s, int n) |
| { |
| register unsigned int tmp; |
| #if CACHED_BITSTREAM_READER |
| |
| av_assert2(n>0 && n<=32); |
| if (n > s->bits_left) { |
| #ifdef BITSTREAM_READER_LE |
| refill_32(s, 1); |
| #else |
| refill_32(s, 0); |
| #endif |
| if (s->bits_left < 32) |
| s->bits_left = n; |
| } |
| |
| #ifdef BITSTREAM_READER_LE |
| tmp = get_val(s, n, 1); |
| #else |
| tmp = get_val(s, n, 0); |
| #endif |
| #else |
| OPEN_READER(re, s); |
| av_assert2(n>0 && n<=25); |
| UPDATE_CACHE(re, s); |
| tmp = SHOW_UBITS(re, s, n); |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| #endif |
| av_assert2(tmp < UINT64_C(1) << n); |
| return tmp; |
| } |
| |
| /** |
| * Read 0-25 bits. |
| */ |
| static av_always_inline int get_bitsz(GetBitContext *s, int n) |
| { |
| return n ? get_bits(s, n) : 0; |
| } |
| |
| static inline unsigned int get_bits_le(GetBitContext *s, int n) |
| { |
| #if CACHED_BITSTREAM_READER |
| av_assert2(n>0 && n<=32); |
| if (n > s->bits_left) { |
| refill_32(s, 1); |
| if (s->bits_left < 32) |
| s->bits_left = n; |
| } |
| |
| return get_val(s, n, 1); |
| #else |
| register int tmp; |
| OPEN_READER(re, s); |
| av_assert2(n>0 && n<=25); |
| UPDATE_CACHE_LE(re, s); |
| tmp = SHOW_UBITS_LE(re, s, n); |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| return tmp; |
| #endif |
| } |
| |
| /** |
| * Show 1-25 bits. |
| */ |
| static inline unsigned int show_bits(GetBitContext *s, int n) |
| { |
| register unsigned int tmp; |
| #if CACHED_BITSTREAM_READER |
| if (n > s->bits_left) |
| #ifdef BITSTREAM_READER_LE |
| refill_32(s, 1); |
| #else |
| refill_32(s, 0); |
| #endif |
| |
| tmp = show_val(s, n); |
| #else |
| OPEN_READER_NOSIZE(re, s); |
| av_assert2(n>0 && n<=25); |
| UPDATE_CACHE(re, s); |
| tmp = SHOW_UBITS(re, s, n); |
| #endif |
| return tmp; |
| } |
| |
| static inline void skip_bits(GetBitContext *s, int n) |
| { |
| #if CACHED_BITSTREAM_READER |
| if (n < s->bits_left) |
| skip_remaining(s, n); |
| else { |
| n -= s->bits_left; |
| s->cache = 0; |
| s->bits_left = 0; |
| |
| if (n >= 64) { |
| unsigned skip = (n / 8) * 8; |
| |
| n -= skip; |
| s->index += skip; |
| } |
| #ifdef BITSTREAM_READER_LE |
| refill_64(s, 1); |
| #else |
| refill_64(s, 0); |
| #endif |
| if (n) |
| skip_remaining(s, n); |
| } |
| #else |
| OPEN_READER(re, s); |
| LAST_SKIP_BITS(re, s, n); |
| CLOSE_READER(re, s); |
| #endif |
| } |
| |
| static inline unsigned int get_bits1(GetBitContext *s) |
| { |
| #if CACHED_BITSTREAM_READER |
| if (!s->bits_left) |
| #ifdef BITSTREAM_READER_LE |
| refill_64(s, 1); |
| #else |
| refill_64(s, 0); |
| #endif |
| |
| #ifdef BITSTREAM_READER_LE |
| return get_val(s, 1, 1); |
| #else |
| return get_val(s, 1, 0); |
| #endif |
| #else |
| unsigned int index = s->index; |
| uint8_t result = s->buffer[index >> 3]; |
| #ifdef BITSTREAM_READER_LE |
| result >>= index & 7; |
| result &= 1; |
| #else |
| result <<= index & 7; |
| result >>= 8 - 1; |
| #endif |
| #if !UNCHECKED_BITSTREAM_READER |
| if (s->index < s->size_in_bits_plus8) |
| #endif |
| index++; |
| s->index = index; |
| |
| return result; |
| #endif |
| } |
| |
| static inline unsigned int show_bits1(GetBitContext *s) |
| { |
| return show_bits(s, 1); |
| } |
| |
| static inline void skip_bits1(GetBitContext *s) |
| { |
| skip_bits(s, 1); |
| } |
| |
| /** |
| * Read 0-32 bits. |
| */ |
| static inline unsigned int get_bits_long(GetBitContext *s, int n) |
| { |
| av_assert2(n>=0 && n<=32); |
| if (!n) { |
| return 0; |
| #if CACHED_BITSTREAM_READER |
| } |
| return get_bits(s, n); |
| #else |
| } else if (n <= MIN_CACHE_BITS) { |
| return get_bits(s, n); |
| } else { |
| #ifdef BITSTREAM_READER_LE |
| unsigned ret = get_bits(s, 16); |
| return ret | (get_bits(s, n - 16) << 16); |
| #else |
| unsigned ret = get_bits(s, 16) << (n - 16); |
| return ret | get_bits(s, n - 16); |
| #endif |
| } |
| #endif |
| } |
| |
| /** |
| * Read 0-64 bits. |
| */ |
| static inline uint64_t get_bits64(GetBitContext *s, int n) |
| { |
| if (n <= 32) { |
| return get_bits_long(s, n); |
| } else { |
| #ifdef BITSTREAM_READER_LE |
| uint64_t ret = get_bits_long(s, 32); |
| return ret | (uint64_t) get_bits_long(s, n - 32) << 32; |
| #else |
| uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; |
| return ret | get_bits_long(s, 32); |
| #endif |
| } |
| } |
| |
| /** |
| * Read 0-32 bits as a signed integer. |
| */ |
| static inline int get_sbits_long(GetBitContext *s, int n) |
| { |
| // sign_extend(x, 0) is undefined |
| if (!n) |
| return 0; |
| |
| return sign_extend(get_bits_long(s, n), n); |
| } |
| |
| /** |
| * Show 0-32 bits. |
| */ |
| static inline unsigned int show_bits_long(GetBitContext *s, int n) |
| { |
| if (n <= MIN_CACHE_BITS) { |
| return show_bits(s, n); |
| } else { |
| GetBitContext gb = *s; |
| return get_bits_long(&gb, n); |
| } |
| } |
| |
| static inline int init_get_bits_xe(GetBitContext *s, const uint8_t *buffer, |
| int bit_size, int is_le) |
| { |
| int buffer_size; |
| int ret = 0; |
| |
| if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) { |
| bit_size = 0; |
| buffer = NULL; |
| ret = AVERROR_INVALIDDATA; |
| } |
| |
| buffer_size = (bit_size + 7) >> 3; |
| |
| s->buffer = buffer; |
| s->size_in_bits = bit_size; |
| s->size_in_bits_plus8 = bit_size + 8; |
| s->buffer_end = buffer + buffer_size; |
| s->index = 0; |
| |
| #if CACHED_BITSTREAM_READER |
| s->cache = 0; |
| s->bits_left = 0; |
| refill_64(s, is_le); |
| #endif |
| |
| return ret; |
| } |
| |
| /** |
| * Initialize GetBitContext. |
| * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes |
| * larger than the actual read bits because some optimized bitstream |
| * readers read 32 or 64 bit at once and could read over the end |
| * @param bit_size the size of the buffer in bits |
| * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. |
| */ |
| static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer, |
| int bit_size) |
| { |
| #ifdef BITSTREAM_READER_LE |
| return init_get_bits_xe(s, buffer, bit_size, 1); |
| #else |
| return init_get_bits_xe(s, buffer, bit_size, 0); |
| #endif |
| } |
| |
| /** |
| * Initialize GetBitContext. |
| * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes |
| * larger than the actual read bits because some optimized bitstream |
| * readers read 32 or 64 bit at once and could read over the end |
| * @param byte_size the size of the buffer in bytes |
| * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. |
| */ |
| static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer, |
| int byte_size) |
| { |
| if (byte_size > INT_MAX / 8 || byte_size < 0) |
| byte_size = -1; |
| return init_get_bits(s, buffer, byte_size * 8); |
| } |
| |
| static inline int init_get_bits8_le(GetBitContext *s, const uint8_t *buffer, |
| int byte_size) |
| { |
| if (byte_size > INT_MAX / 8 || byte_size < 0) |
| byte_size = -1; |
| return init_get_bits_xe(s, buffer, byte_size * 8, 1); |
| } |
| |
| static inline const uint8_t *align_get_bits(GetBitContext *s) |
| { |
| int n = -get_bits_count(s) & 7; |
| if (n) |
| skip_bits(s, n); |
| return s->buffer + (s->index >> 3); |
| } |
| |
| /** |
| * If the vlc code is invalid and max_depth=1, then no bits will be removed. |
| * If the vlc code is invalid and max_depth>1, then the number of bits removed |
| * is undefined. |
| */ |
| #define GET_VLC(code, name, gb, table, bits, max_depth) \ |
| do { \ |
| int n, nb_bits; \ |
| unsigned int index; \ |
| \ |
| index = SHOW_UBITS(name, gb, bits); \ |
| code = table[index].sym; \ |
| n = table[index].len; \ |
| \ |
| if (max_depth > 1 && n < 0) { \ |
| LAST_SKIP_BITS(name, gb, bits); \ |
| UPDATE_CACHE(name, gb); \ |
| \ |
| nb_bits = -n; \ |
| \ |
| index = SHOW_UBITS(name, gb, nb_bits) + code; \ |
| code = table[index].sym; \ |
| n = table[index].len; \ |
| if (max_depth > 2 && n < 0) { \ |
| LAST_SKIP_BITS(name, gb, nb_bits); \ |
| UPDATE_CACHE(name, gb); \ |
| \ |
| nb_bits = -n; \ |
| \ |
| index = SHOW_UBITS(name, gb, nb_bits) + code; \ |
| code = table[index].sym; \ |
| n = table[index].len; \ |
| } \ |
| } \ |
| SKIP_BITS(name, gb, n); \ |
| } while (0) |
| |
| #define GET_RL_VLC(level, run, name, gb, table, bits, \ |
| max_depth, need_update) \ |
| do { \ |
| int n, nb_bits; \ |
| unsigned int index; \ |
| \ |
| index = SHOW_UBITS(name, gb, bits); \ |
| level = table[index].level; \ |
| n = table[index].len; \ |
| \ |
| if (max_depth > 1 && n < 0) { \ |
| SKIP_BITS(name, gb, bits); \ |
| if (need_update) { \ |
| UPDATE_CACHE(name, gb); \ |
| } \ |
| \ |
| nb_bits = -n; \ |
| \ |
| index = SHOW_UBITS(name, gb, nb_bits) + level; \ |
| level = table[index].level; \ |
| n = table[index].len; \ |
| if (max_depth > 2 && n < 0) { \ |
| LAST_SKIP_BITS(name, gb, nb_bits); \ |
| if (need_update) { \ |
| UPDATE_CACHE(name, gb); \ |
| } \ |
| nb_bits = -n; \ |
| \ |
| index = SHOW_UBITS(name, gb, nb_bits) + level; \ |
| level = table[index].level; \ |
| n = table[index].len; \ |
| } \ |
| } \ |
| run = table[index].run; \ |
| SKIP_BITS(name, gb, n); \ |
| } while (0) |
| |
| /* Return the LUT element for the given bitstream configuration. */ |
| static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits, |
| const VLCElem *table) |
| { |
| unsigned idx; |
| |
| *nb_bits = -*n; |
| idx = show_bits(s, *nb_bits) + code; |
| *n = table[idx].len; |
| |
| return table[idx].sym; |
| } |
| |
| /** |
| * Parse a vlc code. |
| * @param bits is the number of bits which will be read at once, must be |
| * identical to nb_bits in init_vlc() |
| * @param max_depth is the number of times bits bits must be read to completely |
| * read the longest vlc code |
| * = (max_vlc_length + bits - 1) / bits |
| * @returns the code parsed or -1 if no vlc matches |
| */ |
| static av_always_inline int get_vlc2(GetBitContext *s, const VLCElem *table, |
| int bits, int max_depth) |
| { |
| #if CACHED_BITSTREAM_READER |
| int nb_bits; |
| unsigned idx = show_bits(s, bits); |
| int code = table[idx].sym; |
| int n = table[idx].len; |
| |
| if (max_depth > 1 && n < 0) { |
| skip_remaining(s, bits); |
| code = set_idx(s, code, &n, &nb_bits, table); |
| if (max_depth > 2 && n < 0) { |
| skip_remaining(s, nb_bits); |
| code = set_idx(s, code, &n, &nb_bits, table); |
| } |
| } |
| skip_remaining(s, n); |
| |
| return code; |
| #else |
| int code; |
| |
| OPEN_READER(re, s); |
| UPDATE_CACHE(re, s); |
| |
| GET_VLC(code, re, s, table, bits, max_depth); |
| |
| CLOSE_READER(re, s); |
| |
| return code; |
| #endif |
| } |
| |
| static inline int decode012(GetBitContext *gb) |
| { |
| int n; |
| n = get_bits1(gb); |
| if (n == 0) |
| return 0; |
| else |
| return get_bits1(gb) + 1; |
| } |
| |
| static inline int decode210(GetBitContext *gb) |
| { |
| if (get_bits1(gb)) |
| return 0; |
| else |
| return 2 - get_bits1(gb); |
| } |
| |
| static inline int get_bits_left(GetBitContext *gb) |
| { |
| return gb->size_in_bits - get_bits_count(gb); |
| } |
| |
| static inline int skip_1stop_8data_bits(GetBitContext *gb) |
| { |
| if (get_bits_left(gb) <= 0) |
| return AVERROR_INVALIDDATA; |
| |
| while (get_bits1(gb)) { |
| skip_bits(gb, 8); |
| if (get_bits_left(gb) <= 0) |
| return AVERROR_INVALIDDATA; |
| } |
| |
| return 0; |
| } |
| |
| #endif /* AVCODEC_GET_BITS_H */ |
